Thank you for the remark. Actually I have tested the behaviour when the GridView loses focus. For example when I click on a Button outside of the GridView. The EditAction is Cancel when the GridView loses focus, not when the next row is selected. In that case the EditAction is Commit by design.
I would suggest you to subscribe for the RowValidating event instead and try to implement your logic there. Please note that you could cancel the edit using the CancelEdit() event of the RadGridView.
the Telerik team